Free everyday calculators
Practical online tools for common US daily tasks.
Calculate salary conversions, tips, sales tax, mortgage payments, BMI with feet and pounds, time zones, currency estimates, and more. No sign-up required.
Privacy-first file tools
Selected files stay in your browser.
Compress and convert images, prepare files for print, merge or extract PDF pages, and remove common image metadata. No account and no file upload to KokoroFlow.
Full calculators
Open the full version of each calculator.
These tools have their own dedicated page with a complete input set, worked examples, and detailed guidance. Tap a card to open it.
Tip Calculator
Estimate tip, total, and per-person amount for restaurants or deliveries.
Sales Tax Calculator
Enter a price and local tax rate to estimate the final checkout total.
Currency Converter
Convert common currencies using a current public reference rate.
Mortgage Calculator
Estimate a US-style monthly principal and interest payment, with an extra-payment option.
Password Generator
Generate a local random password with optional symbols and similar-character exclusion.
Sudoku Generator
Make printable sudoku puzzles with exactly one solution, easy to hard, and download a print-ready PDF with answers.
JSON Formatter & Merger
Pretty-print, validate, and deep-merge JSON objects entirely in your browser.
PC First Aid
Answer three questions about a computer problem and get a calm, safety-first next step before you reset or repair.
Printer Offline Troubleshooter
Answer four questions and get an ordered checklist to bring a Wi-Fi or USB printer back online.
Image to Text (OCR)
Extract text from a photo or screenshot in English or Chinese, processed entirely on your device.
Decision calculators
Should you do it? Run the numbers first.
These tools are built around a specific decision, not just a formula — enter your situation and see which option comes out ahead.
Rent vs. Buy Calculator
Compare the true long-term cost of renting versus buying, including taxes, maintenance, and opportunity cost.
Should I Take This Project?
Weigh a freelance offer's pay against your time, expenses, and opportunity cost before saying yes.
Localized calculators
Numbers that actually match where you live.
State and local rules can change salary, tax, and take-home pay significantly. These versions build the local rules in — pick your state to get started.
Printable worksheets
Free templates you can print and use today.
Simple, ad-light PDF and print-ready templates for common life admin — no account, no editing software required.
Printable Worksheets Library
Browse every free printable — checklists, budget sheets, and planning templates in one place.
Moving Checklist
An 8-week countdown checklist for moving house, from booking movers to updating your address.
Monthly Budget Worksheet
A simple one-page budget template to track income, fixed costs, and savings by hand.
File & photo tools
Clean up photos, files, and bookmarks.
Every tool below runs entirely in your browser — nothing is uploaded to a server.
Duplicate Image Finder
Scan a batch of photos and instantly spot exact duplicates and visually similar images.
Batch File Renamer
Rename dozens of files at once with prefixes, sequential numbers, or find-and-replace, then download as a ZIP.
Folder Comparison Report
Compare two folders and see what's only in A, only in B, or different — a report only, nothing is copied or synced.
Bookmark Cleaner & Organizer
Import your exported bookmarks, remove duplicates, and export a cleaned-up file.
QR Code Generator
Create a QR code for a link, Wi-Fi, LINE/WhatsApp/Telegram chat, social profile, or contact card.
Fuel Economy Converter
Calculate real-world MPG from a trip, convert MPG ↔ L/100km, or compare two vehicles' annual fuel cost.
Return or Keep Calculator
Compare returning, reselling, or keeping an item once shipping, fees, and your time are counted.
Printer Cost per Page
Real cost per printed page, plus the break-even point between two printers or a print shop.
Real-Use Unit Cost
What a product actually costs per use once the share you never finish is accounted for.
Partial-Month Utilities Split
Split a bill fairly by days lived there when someone moved in or out mid-cycle.
Time Zone Converter
Convert a time across multiple time zones at once, with automatic daylight saving handling.
Quick tools
No dedicated page needed — use these right here.
These simple utilities run entirely on this page.
Random Picker
Enter a list, or use source count for choices like 12 choose 3.
Unit Converter
Common US conversions: inches, feet, miles, pounds, and metric units.
Word Counter
Count words, characters, sentences, and estimated reading time.